[UT, HT] Computers

[nik1979]

Are UT and HT rules for computers interchangable/can you mix and match?

if possible which should I use?
UT uses 5lbs increments, while HT uses 4lbs increment.
HT has the option to use cheaper tech at -1 complexity but at 1/20th cost.

any Idea what volume should I use?
If I go by ISW volume to mass, which of the spec. trade goods should I use? (electronics, precision tools etc.)?

Thanks in advance,